The present invention relates to an endoscope, and particularly to an endoscope capable of directing liquid ejected from a tip end thereof at a predetermined angle.
Generally, an endoscope unit is provided with a liquid channel arranged in parallel with an axis of the endoscope, through which liquid such as water is conveyed, and an aperture at a front end thereof to outlet the liquid, so that an object region to be observed, having body fluid, blood, and the like thereon, can be cleaned with the liquid injected through the aperture. Examples of such an endoscope unit with an aperture at a distal end thereof is disclosed in Japanese Patent Provisional Publication Nos. 2001-292958 and BE16-292685. The endoscope unit disclosed in the former publication is provided with an aperture that is opened to a straight front of a distal portion of the endoscope unit. The endoscope unit disclosed in the latter publication is provided with a treatment tool to be inserted through an instrument channel of the endoscope, which is equipped at a distal portion of an insulated flexible sheath. The treatment tool includes a high-frequency electrode, which is protrusible from the distal portion of the sheath, to incise or coagulate mucous membrane of in vivo tissues, and an aperture is formed on a distal surface of the distal portion, through which water to clean the mucous membrane is ejected.
In such configurations, however, the water through the aperture is simply ejected toward the straight front, and not ejected toward a center of a scope of observation, as the aperture is provided in an offset position with respect to an axis of the distal portion of the endoscope unit. Therefore, it is difficult to aim the water at a portion of the mucous membrane to be cleaned. In order to aim the water at the portion to be cleaned, an entire inserted portion is required to be shifted. In this case, the scope of observation is shifted as well, and thus it is still difficult to aim the water at the portion to be cleaned, and removing the body fluid from the mucous membranes is often time-consuming.
In consideration of the above, the aperture may be arranged in an oblique orientation with respect to the axis of the inserted portion, so that the water therethrough can be ejected in an angled direction. With this configuration, the water may be ejected to the center of the scope of observation when the aperture is spaced from the aimed portion of the mucous membrane for a predetermined distance. However, once the aperture is spaced from the aimed portion for a greater or a smaller distance, the ejected water does not meet the center of the observation scope. Further, as the aperture arranged in the oblique orientation requires greater space in the distal portion, other features of the endoscope may be limited. In an endoscope unit with a treatment tool, such as disclosed in the latter publication, a diameter of the treatment tool is generally configured to be approximately in a range from 2 to 3 mm. Therefore, arranging the aperture in the oblique orientation in the range is even more difficult. Thus, configuring the distal portion of the endoscope unit to allow the water therethrough to be ejected in a desired direction has been difficult.